1. Field of the Invention
The present invention relates to a video signal processing circuit incorporated in an integrated circuit, which receives a digital camera signal obtained through an A/D conversion of an analog camera signal which is outputted by an image sensor, and performs a digital signal processing so as to produce a luminance signal and a color signal.
2. Description of the Prior Art
A video camera having an electronic zoom function is disclosed in the third section with entitled "A Digital Processing Technique for a VTR with Camera" of the proceedings for the lecture meeting in the name of "making a video camera high performance and high quality" held under the promotion of Giken Joho Senta on Nov. 19 and 20, 1990. In these proceedings, there is disclosed a technique for enlarging lines within a zoom designation area set by an electronic zoom in both a horizontal direction and a vertical direction by means of interpolation. Such an electronic zoom function performs at a succeeding stage of a signal processing at the same timing as in an electronic image stabilizer for compact camcorder.
Space saving does not become a problem in a case where a plurality of integrated circuits are used for the signal processing and the electronic zooming as done in the prior art as described above. However, a problem occurs in the space saving in a case where it is intended to incorporate respective functions of the signal processing and the electronic zooming in a single integrated circuit chip. A portion that needs a large space in incorporating the functions in a single integrated circuit chip is a portion wherein line memories are to be formed, and therefore, if the number of line memories is increased, a space of an integrated circuit cannot be reduced.
In the above described prior art, at least two line memories are required for signal processings of synchronization of color signals, forming of a vertical aperture signal, and a total of etc., and three line memories are required for the luminance signal and two differential color signals in the electronic zoom portion.